<!DOCTYPE html>



  


<html class="theme-next gemini use-motion" lang="en">
<head><meta name="generator" content="Hexo 3.9.0">
  <meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<meta name="theme-color" content="#222">









<meta http-equiv="Cache-Control" content="no-transform">
<meta http-equiv="Cache-Control" content="no-siteapp">
















  
  
  <link href="/lib/fancybox/source/jquery.fancybox.css?v=2.1.5" rel="stylesheet" type="text/css">







<link href="/lib/font-awesome/css/font-awesome.min.css?v=4.6.2" rel="stylesheet" type="text/css">

<link href="/css/main.css?v=5.1.4" rel="stylesheet" type="text/css">


  <link rel="apple-touch-icon" sizes="180x180" href="/images/apple-touch-icon-next.png?v=5.1.4">


  <link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-xm.ico?v=5.1.4">


  <link rel="icon" type="image/png" sizes="16x16" href="/images/favicon-xm.ico?v=5.1.4">


  <link rel="mask-icon" href="/images/logo.svg?v=5.1.4" color="#222">





  <meta name="keywords" content="Hexo, NexT">










<meta name="description" content="数据编码数值数据的编码">
<meta property="og:type" content="article">
<meta property="og:title" content="计算机中的数据表示">
<meta property="og:url" content="http://yoursite.com/2020/08/09/计算机中的数据表示/index.html">
<meta property="og:site_name" content="Ming">
<meta property="og:description" content="数据编码数值数据的编码">
<meta property="og:locale" content="en">
<meta property="og:image" content="http://ww1.sinaimg.cn/large/005VT09Qly1ghku43uslrj31hk2qutl8.jpg">
<meta property="og:updated_time" content="2020-08-25T01:56:37.441Z">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="计算机中的数据表示">
<meta name="twitter:description" content="数据编码数值数据的编码">
<meta name="twitter:image" content="http://ww1.sinaimg.cn/large/005VT09Qly1ghku43uslrj31hk2qutl8.jpg">



<script type="text/javascript" id="hexo.configurations">
  var NexT = window.NexT || {};
  var CONFIG = {
    root: '/',
    scheme: 'Gemini',
    version: '5.1.4',
    sidebar: {"position":"left","display":"post","offset":12,"b2t":false,"scrollpercent":false,"onmobile":false},
    fancybox: true,
    tabs: true,
    motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}},
    duoshuo: {
      userId: '0',
      author: 'Author'
    },
    algolia: {
      applicationID: '',
      apiKey: '',
      indexName: '',
      hits: {"per_page":10},
      labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
    }
  };
</script>



  <link rel="canonical" href="http://yoursite.com/2020/08/09/计算机中的数据表示/">





  <title>计算机中的数据表示 | Ming</title>
  





  <script type="text/javascript">
    var _hmt = _hmt || [];
    (function() {
      var hm = document.createElement("script");
      hm.src = "https://hm.baidu.com/hm.js?2ff12830577cde1e94dd80bdcf083398";
      var s = document.getElementsByTagName("script")[0];
      s.parentNode.insertBefore(hm, s);
    })();
  </script>




</head>

<body itemscope itemtype="http://schema.org/WebPage" lang="en">

  
  
    
  

  <div class="container sidebar-position-left page-post-detail">
    <div class="headband"></div>

    <header id="header" class="header" itemscope itemtype="http://schema.org/WPHeader">
      <div class="header-inner"><div class="site-brand-wrapper">
  <div class="site-meta ">
    

    <div class="custom-logo-site-title">
      <a href="/" class="brand" rel="start">
        <span class="logo-line-before"><i></i></span>
        <span class="site-title">Ming</span>
        <span class="logo-line-after"><i></i></span>
      </a>
    </div>
      
        <p class="site-subtitle"></p>
      
  </div>

  <div class="site-nav-toggle">
    <button>
      <span class="btn-bar"></span>
      <span class="btn-bar"></span>
      <span class="btn-bar"></span>
    </button>
  </div>
</div>

<nav class="site-nav">
  

  
    <ul id="menu" class="menu">
      
        
        <li class="menu-item menu-item-home">
          <a href="/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-home"></i> <br>
            
            Home
          </a>
        </li>
      
        
        <li class="menu-item menu-item-about">
          <a href="/about/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-user"></i> <br>
            
            About
          </a>
        </li>
      
        
        <li class="menu-item menu-item-categories">
          <a href="/categories/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-th"></i> <br>
            
            Categories
          </a>
        </li>
      
        
        <li class="menu-item menu-item-archives">
          <a href="/archives/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-archive"></i> <br>
            
            Archives
          </a>
        </li>
      
        
        <li class="menu-item menu-item-commonweal">
          <a href="/404/" rel="section">
            
              <i class="menu-item-icon fa fa-fw fa-heartbeat"></i> <br>
            
            Commonweal 404
          </a>
        </li>
      

      
        <li class="menu-item menu-item-search">
          
            <a href="javascript:;" class="popup-trigger">
          
            
              <i class="menu-item-icon fa fa-search fa-fw"></i> <br>
            
            Search
          </a>
        </li>
      
    </ul>
  

  
    <div class="site-search">
      
  <div class="popup search-popup local-search-popup">
  <div class="local-search-header clearfix">
    <span class="search-icon">
      <i class="fa fa-search"></i>
    </span>
    <span class="popup-btn-close">
      <i class="fa fa-times-circle"></i>
    </span>
    <div class="local-search-input-wrapper">
      <input autocomplete="off" placeholder="Searching..." spellcheck="false" type="text" id="local-search-input">
    </div>
  </div>
  <div id="local-search-result"></div>
</div>



    </div>
  
</nav>



 </div>
    </header>

    <main id="main" class="main">
      <div class="main-inner">
        <div class="content-wrap">
          <div id="content" class="content">
            

  <div id="posts" class="posts-expand">
    

  

  
  
  

  <article class="post post-type-normal" itemscope itemtype="http://schema.org/Article">
  
  
  
  <div class="post-block">
    <link itemprop="mainEntityOfPage" href="http://yoursite.com/2020/08/09/计算机中的数据表示/">

    <span hidden itemprop="author" itemscope itemtype="http://schema.org/Person">
      <meta itemprop="name" content="Ming">
      <meta itemprop="description" content>
      <meta itemprop="image" content="/images/arina.jpg">
    </span>

    <span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization">
      <meta itemprop="name" content="Ming">
    </span>

    
      <header class="post-header">

        
        
          <h1 class="post-title" itemprop="name headline">计算机中的数据表示</h1>
        

        <div class="post-meta">
          <span class="post-time">
            
              <span class="post-meta-item-icon">
                <i class="fa fa-calendar-o"></i>
              </span>
              
                <span class="post-meta-item-text">Posted on</span>
              
              <time title="Post created" itemprop="dateCreated datePublished" datetime="2020-08-09T20:30:19+08:00">
                2020-08-09
              </time>
            

            

            
          </span>

          
            <span class="post-category">
            
              <span class="post-meta-divider">|</span>
            
              <span class="post-meta-item-icon">
                <i class="fa fa-folder-o"></i>
              </span>
              
                <span class="post-meta-item-text">In</span>
              
              
                <span itemprop="about" itemscope itemtype="http://schema.org/Thing">
                  <a href="/categories/计组/" itemprop="url" rel="index">
                    <span itemprop="name">计组</span>
                  </a>
                </span>

                
                
              
            </span>
          

          
            
          

          
          

          

          
            <div class="post-wordcount">
              
                
                <span class="post-meta-item-icon">
                  <i class="fa fa-file-word-o"></i>
                </span>
                
                  <span class="post-meta-item-text">Words count in article&#58;</span>
                
                <span title="Words count in article">
                  834
                </span>
              

              
                <span class="post-meta-divider">|</span>
              

              
                <span class="post-meta-item-icon">
                  <i class="fa fa-clock-o"></i>
                </span>
                
                  <span class="post-meta-item-text">Reading time &asymp;</span>
                
                <span title="Reading time">
                  2
                </span>
              
            </div>
          

          

        </div>
      </header>
    

    
    
    
    <div class="post-body" itemprop="articleBody">

      
      

      
        <h2 id="数据编码"><a href="#数据编码" class="headerlink" title="数据编码"></a>数据编码</h2><h3 id="数值数据的编码"><a href="#数值数据的编码" class="headerlink" title="数值数据的编码"></a>数值数据的编码</h3><a id="more"></a>

<ul>
<li><p>数据</p>
<ul>
<li><p>分类</p>
<ul>
<li><p>根据小数点</p>
<ul>
<li><p>定点数</p>
<ul>
<li><p>定点整数（纯整数）</p>
<ul>
<li>符号位</li>
<li>数值位</li>
<li>小数点位</li>
<li>编码表示范围</li>
</ul>
</li>
<li><p>定点小数</p>
<ul>
<li>符号位</li>
<li>数值位</li>
<li>小数点位</li>
<li>编码表示范围</li>
</ul>
</li>
</ul>
</li>
<li><p>浮点数</p>
<ul>
<li>数符</li>
<li>阶符</li>
<li>阶码</li>
<li>尾数</li>
</ul>
</li>
</ul>
</li>
<li><p>根据符号</p>
<ul>
<li>无符号数</li>
<li>有符号数</li>
</ul>
</li>
</ul>
</li>
<li><p>进制转换</p>
<ul>
<li>整数部分</li>
<li>小数部分不断×2取整数部分做尾数直到小数部分为0</li>
</ul>
</li>
</ul>
</li>
<li><p>编码</p>
<ul>
<li><p>原码</p>
<ul>
<li><p>符号位</p>
<ul>
<li><p>最高位</p>
<ul>
<li><p>1</p>
<ul>
<li>负</li>
</ul>
</li>
<li><p>0</p>
<ul>
<li>正</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>数值0</p>
<ul>
<li>两种表示</li>
</ul>
</li>
<li><p>原码和真值的转换</p>
<ul>
<li>把符号位改成﹢或-</li>
</ul>
</li>
<li><p>优劣</p>
<ul>
<li><p>优势</p>
<ul>
<li>简单直观</li>
<li>转换容易</li>
</ul>
</li>
<li><p>劣势</p>
<ul>
<li><p>0的表示不唯一</p>
</li>
<li><p>加减复杂</p>
</li>
<li><p>乘除简单</p>
<ul>
<li>真值相乘判断正负</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>n位源码的表示范围</p>
<ul>
<li>整数</li>
<li>纯小数</li>
</ul>
</li>
</ul>
</li>
<li><p>补码</p>
<ul>
<li><p>作用</p>
<ul>
<li>把减法变成加法</li>
</ul>
</li>
<li><p>整数补码</p>
<ul>
<li><p>值</p>
<ul>
<li><p>正数的补码是其本身</p>
</li>
<li><p>负数的补码计算（以-35为例）</p>
<ul>
<li>将+35原码表示，所有位取反，最低位加1</li>
<li>将-35原码表示，除了符号位所有位取反，最低位加1</li>
<li>将+35原码表示，从低位向高位，找到第一个1不变，之后全部取反</li>
</ul>
</li>
</ul>
</li>
<li><p>表示范围</p>
<ul>
<li><p>最大值和原码最大值相同</p>
</li>
<li><p>最小值比原码最小值小1</p>
<ul>
<li>补码里0的表示只有一种</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>小数补码</p>
<ul>
<li><p>值</p>
<ul>
<li>和整数补码有相同的计算方法</li>
</ul>
</li>
<li><p>表示范围</p>
<ul>
<li>最大值和原码最大值相同</li>
<li>最小值可以取到边界值-1</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>反码</p>
<ul>
<li><p>求补码的过渡</p>
</li>
<li><p>取值</p>
<ul>
<li>正数不变</li>
<li>负数除了符号位所有位按位取反</li>
</ul>
</li>
<li><p>表示范围</p>
<ul>
<li>和原码一样</li>
</ul>
</li>
</ul>
</li>
<li><p>移码</p>
<ul>
<li>数值部分和补码相同</li>
<li>符号部分和补码相反</li>
</ul>
</li>
<li><p>求补运算</p>
<ul>
<li>所有位按位取反，末位加1</li>
</ul>
</li>
<li><p>算数左移/右移</p>
<ul>
<li><p>左移</p>
<ul>
<li>最高位移除，最低位补0</li>
</ul>
</li>
<li><p>右移</p>
<ul>
<li>最高位不变，最低位移除</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
<h3 id="数据的浮点表示"><a href="#数据的浮点表示" class="headerlink" title="数据的浮点表示"></a>数据的浮点表示</h3><ul>
<li><p>浮点数表示法</p>
<ul>
<li><p>概念</p>
<ul>
<li>类似科学计数法</li>
</ul>
</li>
<li><p>组成</p>
<ul>
<li><p>尾数（用补码或原码表示）</p>
<ul>
<li>数值部分</li>
<li>数符部分</li>
</ul>
</li>
<li><p>基数（一般为2，不表示）</p>
</li>
<li><p>阶码（用移码表示）</p>
<ul>
<li>数值部分</li>
<li>数符部分</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>浮点数所表示的数据范围</p>
<ul>
<li><p>浮点数分类</p>
<ul>
<li><p>非规格化浮点数</p>
</li>
<li><p>规格化浮点数</p>
<ul>
<li>将尾数的绝对值限定在某个范围内</li>
<li>规格化浮点数的第一位数值位和数符位必须相反</li>
<li>范围</li>
<li>例题</li>
</ul>
</li>
</ul>
</li>
<li><p>规格化</p>
<ul>
<li>左规</li>
<li>右规</li>
</ul>
</li>
<li><p>溢出</p>
<ul>
<li><p>上溢</p>
<ul>
<li>正</li>
<li>负</li>
</ul>
</li>
<li><p>下溢</p>
<ul>
<li>正</li>
<li>负</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
<h3 id="检错与纠错编码"><a href="#检错与纠错编码" class="headerlink" title="检错与纠错编码"></a>检错与纠错编码</h3><ul>
<li><p>奇偶校验码</p>
<ul>
<li><p>概念</p>
<ul>
<li>事先约定好用奇或偶校验</li>
<li>补一位0或1使其有奇数或偶数个1</li>
</ul>
</li>
<li><p>分类</p>
<ul>
<li><p>水平奇偶校验</p>
</li>
<li><p>垂直奇偶校验</p>
</li>
<li><p>水平垂直奇偶校验</p>
<ul>
<li>水平＋垂直</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><p>海明码</p>
<ul>
<li><p>概念</p>
<ul>
<li>具有一位纠错能力的编码</li>
</ul>
</li>
<li><p>编码距离</p>
</li>
</ul>
</li>
<li><p>循环冗余校验码CRC</p>
<ul>
<li><p>概念</p>
<ul>
<li>做除法运算除尽则编码正确否则余数指出错误位置</li>
</ul>
</li>
<li><p>做法</p>
<ul>
<li><p>获得CRC码</p>
<ul>
<li>将有效信息左移k位（k=生成多项式位数-1）</li>
<li>做除法运算得到余数补到有效信息后面得到CRC码</li>
</ul>
</li>
<li><p>解码</p>
<ul>
<li>用CRC码对生成多项式做除法运算</li>
<li>余数为出错位置（从1开始从右向左数）</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
<img referrerpolicy="no-referrer" src="http://ww1.sinaimg.cn/large/005VT09Qly1ghku43uslrj31hk2qutl8.jpg">

      
    </div>
    
    
    

    

    
      <div>
        <div style="padding: 10px 0; margin: 20px auto; width: 90%; text-align: center;">
  <div>赠人玫瑰，手有余香</div>
  <button id="rewardButton" disable="enable" onclick="var qr = document.getElementById('QR'); if (qr.style.display === 'none') {qr.style.display='block';} else {qr.style.display='none'}">
    <span>Donate</span>
  </button>
  <div id="QR" style="display: none;">

    
      <div id="wechat" style="display: inline-block">
        <img id="wechat_qr" src="/images/wechatpay.png" alt="Ming WeChat Pay">
        <p>WeChat Pay</p>
      </div>
    

    
      <div id="alipay" style="display: inline-block">
        <img id="alipay_qr" src="/images/alipay.jpg" alt="Ming Alipay">
        <p>Alipay</p>
      </div>
    

    

  </div>
</div>

      </div>
    

    

    <footer class="post-footer">
      

      
      
      

      
        <div class="post-nav">
          <div class="post-nav-next post-nav-item">
            
              <a href="/2020/08/09/单元测试/" rel="next" title="单元测试">
                <i class="fa fa-chevron-left"></i> 单元测试
              </a>
            
          </div>

          <span class="post-nav-divider"></span>

          <div class="post-nav-prev post-nav-item">
            
              <a href="/2020/08/11/剑指offer-25/" rel="prev" title="剑指offer-25">
                剑指offer-25 <i class="fa fa-chevron-right"></i>
              </a>
            
          </div>
        </div>
      

      
      
    </footer>
  </div>
  
  
  
  </article>



    <div class="post-spread">
      
    </div>
  </div>


          </div>
          


          

  



        </div>
        
          
  
  <div class="sidebar-toggle">
    <div class="sidebar-toggle-line-wrap">
      <span class="sidebar-toggle-line sidebar-toggle-line-first"></span>
      <span class="sidebar-toggle-line sidebar-toggle-line-middle"></span>
      <span class="sidebar-toggle-line sidebar-toggle-line-last"></span>
    </div>
  </div>

  <aside id="sidebar" class="sidebar">
    
    <div class="sidebar-inner">

      

      
        <ul class="sidebar-nav motion-element">
          <li class="sidebar-nav-toc sidebar-nav-active" data-target="post-toc-wrap">
            Table of Contents
          </li>
          <li class="sidebar-nav-overview" data-target="site-overview-wrap">
            Overview
          </li>
        </ul>
      

      <section class="site-overview-wrap sidebar-panel">
        <div class="site-overview">
          <div class="site-author motion-element" itemprop="author" itemscope itemtype="http://schema.org/Person">
            
              <img class="site-author-image" itemprop="image" src="/images/arina.jpg" alt="Ming">
            
              <p class="site-author-name" itemprop="name">Ming</p>
              <p class="site-description motion-element" itemprop="description">Come on, check me out!</p>
          </div>

          <nav class="site-state motion-element">

            
              <div class="site-state-item site-state-posts">
              
                <a href="/archives/">
              
                  <span class="site-state-item-count">153</span>
                  <span class="site-state-item-name">posts</span>
                </a>
              </div>
            

            
              
              
              <div class="site-state-item site-state-categories">
                <a href="/categories/index.html">
                  <span class="site-state-item-count">16</span>
                  <span class="site-state-item-name">categories</span>
                </a>
              </div>
            

            

          </nav>

          

          
            <div class="links-of-author motion-element">
                
                  <span class="links-of-author-item">
                    <a href="https://github.com/carpediemtal" target="_blank" title="GitHub">
                      
                        <i class="fa fa-fw fa-github"></i>GitHub</a>
                  </span>
                
                  <span class="links-of-author-item">
                    <a href="mail:674602921@qq.com" target="_blank" title="E-Mail">
                      
                        <i class="fa fa-fw fa-envelope"></i>E-Mail</a>
                  </span>
                
                  <span class="links-of-author-item">
                    <a href="qq:674602921" target="_blank" title="QQ">
                      
                        <i class="fa fa-fw fa-qq"></i>QQ</a>
                  </span>
                
                  <span class="links-of-author-item">
                    <a href="overwatchID:SEKAI#51158" target="_blank" title="Overwatch">
                      
                        <i class="fa fa-fw fa-gamepad"></i>Overwatch</a>
                  </span>
                
            </div>
          

          
          

          
          
            <div class="links-of-blogroll motion-element links-of-blogroll-block">
              <div class="links-of-blogroll-title">
                <i class="fa  fa-fw fa-link"></i>
                Links
              </div>
              <ul class="links-of-blogroll-list">
                
                  <li class="links-of-blogroll-item">
                    <a href="http://www.treasurew.com/" title="treasurew" target="_blank">treasurew</a>
                  </li>
                
              </ul>
            </div>
          

          

        </div>
      </section>

      
      <!--noindex-->
        <section class="post-toc-wrap motion-element sidebar-panel sidebar-panel-active">
          <div class="post-toc">

            
              
            

            
              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#数据编码"><span class="nav-number">1.</span> <span class="nav-text">数据编码</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#数值数据的编码"><span class="nav-number">1.1.</span> <span class="nav-text">数值数据的编码</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#数据的浮点表示"><span class="nav-number">1.2.</span> <span class="nav-text">数据的浮点表示</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#检错与纠错编码"><span class="nav-number">1.3.</span> <span class="nav-text">检错与纠错编码</span></a></li></ol></li></ol></div>
            

          </div>
        </section>
      <!--/noindex-->
      

      

    </div>
  </aside>


        
      </div>
    </main>

    <footer id="footer" class="footer">
      <div class="footer-inner">
        <div class="copyright">&copy; 2019 &mdash; <span itemprop="copyrightYear">2020</span>
  <span class="with-love">
    <i class="fa fa-user"></i>
  </span>
  <span class="author" itemprop="copyrightHolder">Ming</span>

  
    <span class="post-meta-divider">|</span>
    <span class="post-meta-item-icon">
      <i class="fa fa-area-chart"></i>
    </span>
    
      <span class="post-meta-item-text">Site words total count&#58;</span>
    
    <span title="Site words total count">64.9k</span>
  
</div>


  <div class="powered-by">Powered by <a class="theme-link" target="_blank" href="https://hexo.io">Hexo</a></div>



  <span class="post-meta-divider">|</span>



  <div class="theme-info">Theme &mdash; <a class="theme-link" target="_blank" href="https://github.com/iissnan/hexo-theme-next">NexT.Gemini</a> v5.1.4</div>




        







        
      </div>
    </footer>

    
      <div class="back-to-top">
        <i class="fa fa-arrow-up"></i>
        
      </div>
    

    

  </div>

  

<script type="text/javascript">
  if (Object.prototype.toString.call(window.Promise) !== '[object Function]') {
    window.Promise = null;
  }
</script>









  


  











  
  
    <script type="text/javascript" src="/lib/jquery/index.js?v=2.1.3"></script>
  

  
  
    <script type="text/javascript" src="/lib/fastclick/lib/fastclick.min.js?v=1.0.6"></script>
  

  
  
    <script type="text/javascript" src="/lib/jquery_lazyload/jquery.lazyload.js?v=1.9.7"></script>
  

  
  
    <script type="text/javascript" src="/lib/velocity/velocity.min.js?v=1.2.1"></script>
  

  
  
    <script type="text/javascript" src="/lib/velocity/velocity.ui.min.js?v=1.2.1"></script>
  

  
  
    <script type="text/javascript" src="/lib/fancybox/source/jquery.fancybox.pack.js?v=2.1.5"></script>
  

  
  
    <script type="text/javascript" src="/lib/canvas-nest/canvas-nest.min.js"></script>
  


  


  <script type="text/javascript" src="/js/src/utils.js?v=5.1.4"></script>

  <script type="text/javascript" src="/js/src/motion.js?v=5.1.4"></script>



  
  


  <script type="text/javascript" src="/js/src/affix.js?v=5.1.4"></script>

  <script type="text/javascript" src="/js/src/schemes/pisces.js?v=5.1.4"></script>



  
  <script type="text/javascript" src="/js/src/scrollspy.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/post-details.js?v=5.1.4"></script>



  


  <script type="text/javascript" src="/js/src/bootstrap.js?v=5.1.4"></script>



  


  




	





  





  












  

  <script type="text/javascript">
    // Popup Window;
    var isfetched = false;
    var isXml = true;
    // Search DB path;
    var search_path = "search.xml";
    if (search_path.length === 0) {
      search_path = "search.xml";
    } else if (/json$/i.test(search_path)) {
      isXml = false;
    }
    var path = "/" + search_path;
    // monitor main search box;

    var onPopupClose = function (e) {
      $('.popup').hide();
      $('#local-search-input').val('');
      $('.search-result-list').remove();
      $('#no-result').remove();
      $(".local-search-pop-overlay").remove();
      $('body').css('overflow', '');
    }

    function proceedsearch() {
      $("body")
        .append('<div class="search-popup-overlay local-search-pop-overlay"></div>')
        .css('overflow', 'hidden');
      $('.search-popup-overlay').click(onPopupClose);
      $('.popup').toggle();
      var $localSearchInput = $('#local-search-input');
      $localSearchInput.attr("autocapitalize", "none");
      $localSearchInput.attr("autocorrect", "off");
      $localSearchInput.focus();
    }

    // search function;
    var searchFunc = function(path, search_id, content_id) {
      'use strict';

      // start loading animation
      $("body")
        .append('<div class="search-popup-overlay local-search-pop-overlay">' +
          '<div id="search-loading-icon">' +
          '<i class="fa fa-spinner fa-pulse fa-5x fa-fw"></i>' +
          '</div>' +
          '</div>')
        .css('overflow', 'hidden');
      $("#search-loading-icon").css('margin', '20% auto 0 auto').css('text-align', 'center');

      $.ajax({
        url: path,
        dataType: isXml ? "xml" : "json",
        async: true,
        success: function(res) {
          // get the contents from search data
          isfetched = true;
          $('.popup').detach().appendTo('.header-inner');
          var datas = isXml ? $("entry", res).map(function() {
            return {
              title: $("title", this).text(),
              content: $("content",this).text(),
              url: $("url" , this).text()
            };
          }).get() : res;
          var input = document.getElementById(search_id);
          var resultContent = document.getElementById(content_id);
          var inputEventFunction = function() {
            var searchText = input.value.trim().toLowerCase();
            var keywords = searchText.split(/[\s\-]+/);
            if (keywords.length > 1) {
              keywords.push(searchText);
            }
            var resultItems = [];
            if (searchText.length > 0) {
              // perform local searching
              datas.forEach(function(data) {
                var isMatch = false;
                var hitCount = 0;
                var searchTextCount = 0;
                var title = data.title.trim();
                var titleInLowerCase = title.toLowerCase();
                var content = data.content.trim().replace(/<[^>]+>/g,"");
                var contentInLowerCase = content.toLowerCase();
                var articleUrl = decodeURIComponent(data.url);
                var indexOfTitle = [];
                var indexOfContent = [];
                // only match articles with not empty titles
                if(title != '') {
                  keywords.forEach(function(keyword) {
                    function getIndexByWord(word, text, caseSensitive) {
                      var wordLen = word.length;
                      if (wordLen === 0) {
                        return [];
                      }
                      var startPosition = 0, position = [], index = [];
                      if (!caseSensitive) {
                        text = text.toLowerCase();
                        word = word.toLowerCase();
                      }
                      while ((position = text.indexOf(word, startPosition)) > -1) {
                        index.push({position: position, word: word});
                        startPosition = position + wordLen;
                      }
                      return index;
                    }

                    indexOfTitle = indexOfTitle.concat(getIndexByWord(keyword, titleInLowerCase, false));
                    indexOfContent = indexOfContent.concat(getIndexByWord(keyword, contentInLowerCase, false));
                  });
                  if (indexOfTitle.length > 0 || indexOfContent.length > 0) {
                    isMatch = true;
                    hitCount = indexOfTitle.length + indexOfContent.length;
                  }
                }

                // show search results

                if (isMatch) {
                  // sort index by position of keyword

                  [indexOfTitle, indexOfContent].forEach(function (index) {
                    index.sort(function (itemLeft, itemRight) {
                      if (itemRight.position !== itemLeft.position) {
                        return itemRight.position - itemLeft.position;
                      } else {
                        return itemLeft.word.length - itemRight.word.length;
                      }
                    });
                  });

                  // merge hits into slices

                  function mergeIntoSlice(text, start, end, index) {
                    var item = index[index.length - 1];
                    var position = item.position;
                    var word = item.word;
                    var hits = [];
                    var searchTextCountInSlice = 0;
                    while (position + word.length <= end && index.length != 0) {
                      if (word === searchText) {
                        searchTextCountInSlice++;
                      }
                      hits.push({position: position, length: word.length});
                      var wordEnd = position + word.length;

                      // move to next position of hit

                      index.pop();
                      while (index.length != 0) {
                        item = index[index.length - 1];
                        position = item.position;
                        word = item.word;
                        if (wordEnd > position) {
                          index.pop();
                        } else {
                          break;
                        }
                      }
                    }
                    searchTextCount += searchTextCountInSlice;
                    return {
                      hits: hits,
                      start: start,
                      end: end,
                      searchTextCount: searchTextCountInSlice
                    };
                  }

                  var slicesOfTitle = [];
                  if (indexOfTitle.length != 0) {
                    slicesOfTitle.push(mergeIntoSlice(title, 0, title.length, indexOfTitle));
                  }

                  var slicesOfContent = [];
                  while (indexOfContent.length != 0) {
                    var item = indexOfContent[indexOfContent.length - 1];
                    var position = item.position;
                    var word = item.word;
                    // cut out 100 characters
                    var start = position - 20;
                    var end = position + 80;
                    if(start < 0){
                      start = 0;
                    }
                    if (end < position + word.length) {
                      end = position + word.length;
                    }
                    if(end > content.length){
                      end = content.length;
                    }
                    slicesOfContent.push(mergeIntoSlice(content, start, end, indexOfContent));
                  }

                  // sort slices in content by search text's count and hits' count

                  slicesOfContent.sort(function (sliceLeft, sliceRight) {
                    if (sliceLeft.searchTextCount !== sliceRight.searchTextCount) {
                      return sliceRight.searchTextCount - sliceLeft.searchTextCount;
                    } else if (sliceLeft.hits.length !== sliceRight.hits.length) {
                      return sliceRight.hits.length - sliceLeft.hits.length;
                    } else {
                      return sliceLeft.start - sliceRight.start;
                    }
                  });

                  // select top N slices in content

                  var upperBound = parseInt('1');
                  if (upperBound >= 0) {
                    slicesOfContent = slicesOfContent.slice(0, upperBound);
                  }

                  // highlight title and content

                  function highlightKeyword(text, slice) {
                    var result = '';
                    var prevEnd = slice.start;
                    slice.hits.forEach(function (hit) {
                      result += text.substring(prevEnd, hit.position);
                      var end = hit.position + hit.length;
                      result += '<b class="search-keyword">' + text.substring(hit.position, end) + '</b>';
                      prevEnd = end;
                    });
                    result += text.substring(prevEnd, slice.end);
                    return result;
                  }

                  var resultItem = '';

                  if (slicesOfTitle.length != 0) {
                    resultItem += "<li><a href='" + articleUrl + "' class='search-result-title'>" + highlightKeyword(title, slicesOfTitle[0]) + "</a>";
                  } else {
                    resultItem += "<li><a href='" + articleUrl + "' class='search-result-title'>" + title + "</a>";
                  }

                  slicesOfContent.forEach(function (slice) {
                    resultItem += "<a href='" + articleUrl + "'>" +
                      "<p class=\"search-result\">" + highlightKeyword(content, slice) +
                      "...</p>" + "</a>";
                  });

                  resultItem += "</li>";
                  resultItems.push({
                    item: resultItem,
                    searchTextCount: searchTextCount,
                    hitCount: hitCount,
                    id: resultItems.length
                  });
                }
              })
            };
            if (keywords.length === 1 && keywords[0] === "") {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-search fa-5x" /></div>'
            } else if (resultItems.length === 0) {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-frown-o fa-5x" /></div>'
            } else {
              resultItems.sort(function (resultLeft, resultRight) {
                if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
                  return resultRight.searchTextCount - resultLeft.searchTextCount;
                } else if (resultLeft.hitCount !== resultRight.hitCount) {
                  return resultRight.hitCount - resultLeft.hitCount;
                } else {
                  return resultRight.id - resultLeft.id;
                }
              });
              var searchResultList = '<ul class=\"search-result-list\">';
              resultItems.forEach(function (result) {
                searchResultList += result.item;
              })
              searchResultList += "</ul>";
              resultContent.innerHTML = searchResultList;
            }
          }

          if ('auto' === 'auto') {
            input.addEventListener('input', inputEventFunction);
          } else {
            $('.search-icon').click(inputEventFunction);
            input.addEventListener('keypress', function (event) {
              if (event.keyCode === 13) {
                inputEventFunction();
              }
            });
          }

          // remove loading animation
          $(".local-search-pop-overlay").remove();
          $('body').css('overflow', '');

          proceedsearch();
        }
      });
    }

    // handle and trigger popup window;
    $('.popup-trigger').click(function(e) {
      e.stopPropagation();
      if (isfetched === false) {
        searchFunc(path, 'local-search-input', 'local-search-result');
      } else {
        proceedsearch();
      };
    });

    $('.popup-btn-close').click(onPopupClose);
    $('.popup').click(function(e){
      e.stopPropagation();
    });
    $(document).on('keyup', function (event) {
      var shouldDismissSearchPopup = event.which === 27 &&
        $('.search-popup').is(':visible');
      if (shouldDismissSearchPopup) {
        onPopupClose();
      }
    });
  </script>





  

  

  

  
  

  

  

  

</body>
</html>
